FlexRay Communication Controller (FlexRAY)
PXN20 Microcontroller Reference Manual, Rev. 1
26-110 Freescale Semiconductor
The enable and disable commands issued by writing 1 to the trigger bit MBCCSRn[EDT]. The transition
that will be triggered by each of these command depends on the current value of the status bit
MBCCSRn[EDS]. If the command triggers the disable transition HD and the message buffer is in one of
the states CCBs, HLckCCBs, or CCRx, the disable transition has no effect (command is ignored) and the
message buffer state is not changed. No notification is given to the application.
Message Buffer Lock and Unlock
The lock and unlock commands issued by writing 1 to the trigger bit MBCCSRn[LCKT]. The transition
that will be triggered by each of these commands depends on the current value of the status bit
MBCCSRn[LCKS]. If the command triggers the lock transition HL while the message buffer is in the state
CCRx, the lock transition has no effect (command is ignored) and message buffer state is not changed. In
this case, the message buffer lock error flag LCK_EF in the CHI Error Flag Register (CHIERFR) is set.
Module Transitions
The module transitions that can be triggered by the controller are described in Table 26-103. Each
transition will be triggered for certain message buffers when the related condition is fulfilled.
Transition Priorities
The application can trigger only one transition at a time. There is no need to specify priorities among them.
As shown in Table 26-104, the module transitions have a higher priority than the application transitions.
For all states except the CCRx state, a module transition and the application lock/unlock transition HL/HU
and can be executed at the same time. The result state is reached by first applying the module transition
and subsequently the application transition to the intermediately reached state. For example, if the message
buffer is in the buffer subscribed state CCBs and the module triggers the slot start transition SLS at the
Table 26-102. Receive Message Buffer Application Transitions
Transition Host Command Condition Description
HE
MBCCSRn[EDT] = 1
MBCCSRn[EDS] = 0 Application triggers message buffer enable.
HD MBCCSRn[EDS] = 1 Application triggers message buffer disable.
HL
MBCCSRn[LCKT] = 1
MBCCSRn[LCKS] = 0 Application triggers message buffer lock.
HU MBCCSRn[LCKS] = 1 Application triggers message buffer unlock.
Table 26-103. Receive Message Buffer Module Transitions
Transition Condition Description
BS slot match and
CycleCounter match
Buffer Subscribed - The message buffer filter matches next slot and cycle.
SLS slot start Slot Start - Start of either Static Slot or Dynamic Slot.
SNS symbol window start or
NIT start
S
ymbol Window or NIT Start - Start of either Symbol Window or NIT.
SSS slot start or
symbol window start or
NIT start
Sl
ot or Segment Start - Start of either Static Slot, Dynamic Slot, Symbol Window,
or NIT.
SU status updated Status Updated - Slot Status field, message buffer status flags, header index
updated. Interrupt flag set.
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